Apple's upcoming watch will be more powerful than the original iPad, it has been claimed.It will use a chip called the S1 specially developed by Apple.

It will be far more powerful than the Apple A4 chip on the original iPad, launched back in early April 2010 by Steve Jobs.

Apple Watch processor is called Apple S1, a 'system-in-package' (SiP) that contains a chip, RAM memory, NAND flash, and other components.

The S1 is 'surprisingly close in performance to the version of Apple's A5 processor found inside the current-generation iPod touch,' according to the 9to5mac..

The A5 processor was also used in other 2011 iOS devices, including the second-generation iPad, the iPhone 4S, the Apple TV and iPad mini.

Apple was highly secretive about the S1 SiP, choosing not to reveal any details about this special component of the Apple Watch during the device's launch, or since.

However, a recent report said Samsung has won the contract to make the chips.

The Watch will also feature a Retina high resolution screen far sharper than that in the opriginal iPad.

9to5mac also says battery life is set to be a key issue for Apple's much anticipated watch - and new claims reveal it will last for 19 hours on a single charge.

Tech blog 9to5mac also claims that in constant use, the battery will die after just four hours.

However, the tech giant is believed to be still working on the software in a bid to improve battery life before its expected ship date in March.

'For the first time, people with knowledge of the Apple Watch's development have provided us with the specific performance targets Apple wants to achieve for the Apple Watch battery, but the actual numbers may fall short of those targets,' 9to5mac's Mark Gurman said.

'According to our sources, Apple opted to use a relatively powerful processor and high-quality screen for the Apple Watch, both of which contribute to significant power drain.'

It says that Apple wanted the Watch to provide roughly 2.5 to 4 hours of active application use versus 19 hours of combined active/passive use, 3 days of pure standby time, or 4 days if left in a sleeping mode,' it says.

However, the site's sources say that Apple will only likely achieve approximately 2-3 days in either the standby or low-power modes.

Running a stripped-down version of iOS codenamed SkiHill, the Apple S1 chip inside the Apple Watch is claimed to be similar in performance to the version of Apple's A5 processor found inside the current-generation iPod touch.

'We're told that Apple has been shooting for roughly 19 hours of mixed usage each day, but that the company may not hit that number in the first generation version.'

Nearly 3,000 test units are said to be currently roaming around as Apple tries to get the battery life of the product right.

It comes just weeks after leaked screenshots revealed the app owners will use on their iPhone.

Called the companion app, the shots reveal several new capabilities of the Apple Watch - including the ability to customise its display with a monogram.

It also shows how users will rearrange the watch's display, moving the apps they want.